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NAT and DNS Issue


We are facing problems with NAT and DNS can anyone help us with proper guidelines.


Problem Summary :

1. In2out packets after certain amount of translations per host.
2. Frequent DNS failures.


Brief description of the fault:

Hope you can help check on a possible NAT issue observed on  a C1111-8P device (and several C1111-4P devices)

The device is s/n: FCZ2514R2BH, which should be covered under policy HW30353 / SLA OSMFFIXNBD

We have been having an issue where Meraki APs that sit behind above devices (which does NATing of the Meraki management and client SSID subnets) report frequent DNS failures

on the Meraki dashboard. On the routers, have observed the ‘NatIn2out’ counters are incrementing as per below output.


Some of the devices are configured as zone-based firewalls, while others just do NAT (eg. FCZ2514R2BH).

Disabling the ZBFW configuration doesn’t make a difference to the DNS failure or NAT drop stats, so it doesn’t appear to be related to the ZBFW configuration as such.

The IOS image on the devices is c1100-universalk9.16.12.05.SPA.bin

Hope you can check and advise on any possible/known issues on this platform/IOS version.

Router#sh platform hardware qfp active statistics drop detail

Last clearing of QFP drops statistics : never


   ID  Global Drop Stats                         Packets                  Octets


  319  BFDoffload                                     24                    2620

  139  Disabled                                        64                    4506

   53  IpFragErr                                        33                  136253

   62  IpTtlExceeded                                459                   23704

   56  IpsecInput                                      36                   18214

   94  Ipv4NoAdj                                     1116                   87389

   19  Ipv4NoRoute                                    61                    6090

  318  MacMcastIpNonmcast                    24                    3920

   69  NAT(NatIn2out)                           700731                94618125

   70  NatOut2in                                  119571                 9250971

   83  ReassTimeout                                   58                   27288

  215  UnconfiguredIpv4Fia                     22491                 8401904

  216  UnconfiguredIpv6Fia                  6511016               558373217

  144  Unresolved                                      2                     316

1 Reply 1

MHM Cisco World


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